Load gripping lift truck



SePt- 4 1956 l.. N. BlcKERsTAr-'F 2,761,579

LOAD GRIFFIN@ LIFT TRUCK Filed Nov. 12, 1953 2 Sheets-Sheet 1 IN VEN TOR. zmnsA Y' N. zcxERs TAFF k @am A T TOR NE'YS' Sept; 4, 1956 l.. N. BlcKERsTAx-F 2,761,579

LOAD GRIPPING LIFT TRUCK Filed Nov. 12, 195s 2 sheets-sheet 2 2, fj l v 9 i l i l' 29 i I| i l 3' I I i i o 'i ol 0 l' El El /0\ `2,2. an. Y 32. 32 f/s L k 214/ \2'3 2 INVENTOR.

I8 4 1 mrDsAYM BrcKEsmFF A TTORNE'YS United States Patent O M LOAD GRIPPING LIFT TRUCK Lindsay N. Bickerstaff, lColumbus, Ga., assignor to Bickerstaf, Inc., a corporation of Georgia Application November 12, 1953, Serial No. 391,484

1 Claim. (Cl. 214-655) This invention relates to Ilift forks and more particuylarly to apparatus for lifting and handling piles of stacked objects, `such as bricks or packages of goods, without the use of pallets and is an improvement on that described and claimed in my previously filed applications for patents, Serial No. 2li,165, led February 15, 1951, and Serial No. 376,827, tiled August 27, 1953, now Patent No. 2,681,741.

A prime object of my invention is to provide apparatus for lifting and transporting piles of stacked objects which shall include deformable gripping means capable of handling such objects of widely varying sizes and shapes.

A further object of my invention is to provide a lift fork embodying rigid tine's carrying rotary gripper shafts having a multiplicity of relatively soft rubber gripper elements mounted thereon which are actuated responsive to rotation of the shaft to grip irregularly shaped objects at a plurality of points, whereby the gripping actionA is increased as the weight of the objects being handled is increased.

A still further object of my invention is to provide a lift fork of the character designated which is -simple of construction and operation, economical of manufacture, and one which is especially adapted for handling objects having irregular surfaces.

Heretofore in the art to which my invention relates, various types of lift forks have been devised. However, so far as l am aware, none have been effective in the handling of articles having irregular surfaces. ln accordance with my invention, l provide a multiplicity of aligned resilient grippers on the tines in position for a plurality thereof to engage an object being handled. The grippers move outwardly of the tines on an arc thus engaging the objects and applying a gripping pressure which increases as the downward force exerted by the weight of the objects is increased.

Apparatus embodying features of my invention is illustrated in the accompanying drawings, forming a part of this application, in which:

Fig. 1 is a plan view of the fork, with parts broken away and in section;

Fig. 2 is a sectional view taken generally along the line lI-ll of Fig. l, showing the gripper elements in release position;

Fig. 3 is a sectional view similar to Fig. 2, but showing the gripper elements in gripping position;

Fig. 4 is a rear elevational View, partly broken away and in section, showing the gripper operating arms in release position; and,

Fig. 5 is a sectional view taken generally along the V-V of Fig. 2.

Referring now to the drawing for a better understanding of my invention, my improved lift fork embodies a tine frame having a rigid base beam at the rear thereof to which are rigidly connected a plurality of forwardly extending tine members 11. Only three tines are Shown Patented Sept. 4, 1956 ICC in the drawing, but it Will be understood that any suitable number rnay be employed. Extending upwardly from each side of the base beam 10 and rigidly secured thereto are upright members 12 and 13 forming a part of the lift frame. Rigidly secured to the base beam 10 and extending upwardly therefrom, inwardly of the members 2 and 13, are lift frame members 14, 16 and 17 which are preferably cylindrical in cross section.

As shown in Figs. l, 2, and 3 the tines 11 comprise an intermediate member 11a which is T-shaped as viewed in cross section and lateral members 11b in the shape of right angles in cross section which face inwardly of the tine frame. Mounted for rotation alongside and inwardly of the lateral members 11b are gripper shafts 18, which are supported in `suitable bearings 19 and 21 at opposite ends of the members 1lb. Mounted on opposite sides of each of the intermediate members 11a are gripper shafts 22 and 23. Suitable bearings 25 and 25a are provided at opposite ends of the members 11a for supporting the gripper shafts 2?. and 23. The gripper shafts 18, 22, and 23 extend through the base beam lll. as shown in Fig. 4, and each has Isecured thereto a rocker arm 24 by which it is rotated.

Mounted for sliding movement on the cylindrical upright members 24, 16 and 17 are -sleeves 26, 27 and 28 respectively which are operatively connected to suitable lifting apparatus, not shown. Extending transversely of 'the lift frame and rigidly secured to the sleeves 26, 27 and 2S, by any suitable means lsuch as bolts 29, is a cross bar 3l. The rocker arms 2d are connected to the cross bar 3l by means of links 32. The links 32 and the rocker arms 2d are so positioned that when the cross bar 31 is raised, the gripper shafts 18, 22 and 23 are rotated in a direction for the gripping units indicated at 33, to be described hereinafter, to engage and hold object 34 to be lifted such as the lower course of a stack of building blocks.

Secured to each of the shafts 18, 22 and 23 by any suitable means lsuch as bolts 36 are a plurality of elon gated plate members 37 and 38. The plate members 37 are provided with recesses 39 at the upper corners thereof and the plate 4members 3S are provided with outwardly projecting members 4l which engage the recesses 39 as shown in Fig. 5. Mounted on the plates 37 and 33 adjacent the lower edges thereof are a multiplicity of closely spaced resilient gripper elements 42. The gripper elements 42 are preferably in the form of cylindrical rubber members which are molded or otherwise secured to the ends of bolt members 43 which pass through the plates 37 and 38 and are secured thereto by means of nuts 44. Also, the gripper elements 42 extend outwardly of the bolt members 43 a distance to permit the same to be deformed whereby they conform to the contour of the objects 34B.

My improved lift fork is operated in a manner similar to that described in my co-pending application Serial No. 376,827. The objects 34 to be lifted and transported, such as building blocks o1' bricks, are stacked, as shown in Fig. 2, so as to provide a space between the lower rows for receiving the tine members 11a and 11b or" the fork. The fork is advanced under the stack with the tines 11a between the intermediate rows and the tines 1lb along the outside rows. The sleeve members 26, 27 and 28 are lifted by suitable lifting apparatus, such as described in the above mentioned co-pendinfy application, thus raising the cross bar 31 and links 32 to rotate the gripper shafts to the gripping position shown in Fig. 3. The gripper elements being in alignment adjacent the lower edge of the plates 37 and 38 are spaced from the gripper shafts, thus causing the elements to move in an are about the shafts into engagement with the articles.

to be handled. As shown in Fig. 5, the resilient ele- `ments 42 are positioned sufficiently close together for a plurality thereof to grip a single article being lifted, thereby permitting each individual element to accommodate itself to the contour of the article. The -members being made of relatively soft rubber, readily accommodate themselves to irregular slopes of articles being handled.

From the foregoing it will be seen that I have devised an improved lift fork which is especially adapted for handling objects which have irregular surfaces. Furthermore by providing gripper elements which move about an arc into engagement With the articles to be lifted, the gripping action is increased in proportion to the Weight of the articles.

While I have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modi cations without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are specifically set forth in the appended claims.

What I claim is:

The combination with a lift fork including a tine frame having a plurality of relatively rigid tines and a plurality of gripper shafts carried by the tines and rotatable with respect thereto, of horizontally extending elongated rigid plates secured along their upper edges to said shafts, and a plurality of independent deformable closely spaced lsubstantially aligned gripper elements adjacent the lower edge of each of said elongated plates, said plates being movable through an arc upon rotation of their associated shafts thereby to bring a plurality of said gripper elements into `securing engagement with a single article being lifted, said gripper elements being in the form of substantially solid cylindrical resilient members with the longitudinal axes thereof parallel to one another and extending substantially normal to said plates.

References Cited in the file of this patent UNITED STATES PATENTS 2,578,016 Rike Dec. 1l, 1951 2,624,608 Rowe Jan. 3, 1953 2,636,768 Hansen Apr. 28, 1953 2,709,016 Schenkelberger May 24, 1955 FOREIGN PATENTS 173,033 Australia Nov. 10, 1952 686,100 Great Britain Jan. 21, 1953 

